This invention relates to memory cells and more particularly relates to control of non-volatile memory cells.
Non-volatile memory cells maintain their contents without the need for an external power supply. In comparison, SRAM, DRAM or other memory technologies lose their contents when the power is switched off. An internal battery is sometimes used to mimic non-volatile memory with SRAM or DRAM; however, an internal battery installation is expensive and cannot guarantee proper operation over long periods of time. It is highly desirable to store certain data, such as boot-up code, chip ID, chip self-repair information, etc., in a non-volatile memory.
The application of non-volatile memory has been hindered by a lack of adequate controls for such memory. Some types of non-volatile memory are degraded over time by the application of excessive voltages. In a memory that uses a verify procedure, voltages necessary to program, erase and verify require repeated application of such voltages. Thus, there is a need for non-volatile memory control that provides increased cell reliability without complicating use of the memory for a user. This invention addresses these needs and provides a solution.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with the present invention as set forth in the remainder of the present application with reference to the drawings.